From patchwork Thu Jun 14 14:42:57 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tim Gardner X-Patchwork-Id: 164949 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from chlorine.canonical.com (chlorine.canonical.com [91.189.94.204]) by ozlabs.org (Postfix) with ESMTP id C260EB704F for ; Fri, 15 Jun 2012 00:42:46 +1000 (EST) Received: from localhost ([127.0.0.1] helo=chlorine.canonical.com) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1SfBFu-0000x7-Ne; Thu, 14 Jun 2012 14:42:38 +0000 Received: from mail.tpi.com ([70.99.223.143]) by chlorine.canonical.com with esmtp (Exim 4.71) (envelope-from ) id 1SfBFp-0000sC-92 for kernel-team@lists.ubuntu.com; Thu, 14 Jun 2012 14:42:33 +0000 Received: from salmon.rtg.net (mail.tpi.com [70.99.223.143]) by mail.tpi.com (Postfix) with ESMTP id 6FBF8320929 for ; Thu, 14 Jun 2012 07:41:49 -0700 (PDT) Received: by salmon.rtg.net (Postfix, from userid 1000) id 190A02045F; Thu, 14 Jun 2012 08:42:59 -0600 (MDT) From: Tim Gardner To: kernel-team@lists.ubuntu.com Subject: [Oneiric SRU PATCH 2/4] hwmon: (fam15h_power) Increase output resolution Date: Thu, 14 Jun 2012 08:42:57 -0600 Message-Id: <1339684979-11086-2-git-send-email-tim.gardner@canonical.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1339684979-11086-1-git-send-email-tim.gardner@canonical.com> References: <1339684979-11086-1-git-send-email-tim.gardner@canonical.com> X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.13 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: kernel-team-bounces@lists.ubuntu.com Errors-To: kernel-team-bounces@lists.ubuntu.com From: Andre Przywara BugLink: http://bugs.launchpad.net/bugs/1009086 On high CPU load the accumulating values in the running_avg_cap register are very low (below 10), so averaging them too early leads to unnecessary poor output resolution. Since we pretend to output micro-Watt we better keep all the bits we have as long as possible. Signed-off-by: Andre Przywara Signed-off-by: Andreas Herrmann Acked-by: Guenter Roeck Signed-off-by: Jean Delvare (cherry picked from commit 941a956b0e387b21f385f486c34ef67576775cfc) Signed-off-by: Tim Gardner --- drivers/hwmon/fam15h_power.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/hwmon/fam15h_power.c b/drivers/hwmon/fam15h_power.c index 9a4c3ab..e8e18ca 100644 --- a/drivers/hwmon/fam15h_power.c +++ b/drivers/hwmon/fam15h_power.c @@ -61,14 +61,14 @@ static ssize_t show_power(struct device *dev, REG_TDP_RUNNING_AVERAGE, &val); running_avg_capture = (val >> 4) & 0x3fffff; running_avg_capture = sign_extend32(running_avg_capture, 21); - running_avg_range = val & 0xf; + running_avg_range = (val & 0xf) + 1; pci_bus_read_config_dword(f4->bus, PCI_DEVFN(PCI_SLOT(f4->devfn), 5), REG_TDP_LIMIT3, &val); tdp_limit = val >> 16; - curr_pwr_watts = tdp_limit + data->base_tdp - - (s32)(running_avg_capture >> (running_avg_range + 1)); + curr_pwr_watts = (tdp_limit + data->base_tdp) << running_avg_range; + curr_pwr_watts -= running_avg_capture; curr_pwr_watts *= data->tdp_to_watts; /* @@ -78,7 +78,7 @@ static ssize_t show_power(struct device *dev, * scaling factor 1/(2^16). For conversion we use * (10^6)/(2^16) = 15625/(2^10) */ - curr_pwr_watts = (curr_pwr_watts * 15625) >> 10; + curr_pwr_watts = (curr_pwr_watts * 15625) >> (10 + running_avg_range); return sprintf(buf, "%u\n", (unsigned int) curr_pwr_watts); } static DEVICE_ATTR(power1_input, S_IRUGO, show_power, NULL);